This invention deals with an improved tool for providing a means for connecting the ends of a pair of sheet metal duct segments. There has been a need for a simple tool to bring together the ends of duct segments every since industry needed to convey air or pressurized fluids from one place to another. The ductwork joins a furnace or a HVAC system with various parts of a building to convey the warm air from the furnace to the various rooms or to convey HVAC air from and to various rooms.
The duct work cannot be formed in a single unitary section because of the need to work around corners, avoid piping of other sorts, walls, and the like and thus, duct work is provided in various segments of length. The segments must be joined together in order for the air to be conveyed thereby. The seams for such a joint must be tight in order to prevent the leakage of the air.
Duct systems are conventionally formed in sections and secured together to form longer spans as needed. A duct section is typically formed of sheet metal into a rectangular shape having four sides and bent or seamed corners at the intersection of the sides. A flange of some sort extends essentially perpendicularly outward from each side at both ends of the duct section. The sections are positioned end-to-end so the flanges of one section align with the flanges of the adjacent section and the aligned flanges are fastened together to form the duct assemblies.
When the ends of two duct segments, shown are 5 and 5′ in FIG. 1A, are to be joined, they are brought together in close proximity and then various tools or devices are employed to finish the final adjustment to bring the pieces to together where they are finally joined by bolts, screws, connectors, and the like.
For this task, the ends of the duct segments are first formed into structures that will abide a fastener or connectors, and such a common joint 1 can be observed in FIG. 2 of this disclosure. Shown in FIG. 2 is a single bend of the sheet metal back onto itself, but it is common to strengthen the joint 1 by providing joints that have been doubly bent as is shown in FIG. 1B. Further, there is shown in FIG. 2, a top view of a portion of a joint that has been formed by bringing the ends of two duct segments together, drawing them tight with a duct stretcher, and then sliding the connector 2 over the joined joints to hold them in place. Quite often, the connectors 2, shown in FIG. 3 have an end tab 4 on each end that is bent down onto the duct after the connector is put in place.
There are several tools in the prior art for tightening such joints and they are shown as a pincher type in FIG. 4A, bar types with adjacent posts in FIG. 4B, and a tool in FIG. 4C that is a double post with a moveable wheel, all of which have several disadvantages. One of the major advantages that these prior art tools share is the fact that they do not have any set-off feature, that is the capability of set off from the ductwork and thus, they are difficult to work with.